280
Organometallics 1990, 9, 280-281
thetic transformations. Our results will be published in due course.
Acknowledgment. Support of this work by a Grantin-Aid from the Ministry of Education, Science and Culture of Japan is gratefully acknowledged. We also thank Shin-Etsu Chemical Co. Ltd. for a gift of trimethylchlorosilane. Registry No. 2a, 78-94-4; 2b, 1629-58-9;2c, 814-78-8; 2d, 2497-21-4; 2e, 94-41-7; 2f, 89-82-7;2g, 5597-27-3;2h, 930-68-7; 3a (coordinated),123992-97-2;3a (noncoordinated),59586-09-3; 3b (coordinated),123992-98-3;3b (noncoordinated),123992-87-0; 3c (coordinated),123992-99-4;3c (noncoordinated),95244-27-2; 3d (coordinated),123993-00-0;3d (noncoordinated),123992-88-1; 3e (coordinated), 123993-01-1; 3e (coordinated isomer l), 123993-02-2;3f (coordinated isomer 2), 124095-67-6;3f (noncoordinated isomer l),123992-91-6;3f (noncoordinated isomer 2), 124095-64-3;3g (coordinated),123993-03-3;3g (noncoordinated), 123992-90-5;4a, 6322-49-2;5a, 98746-44-2;5b, 123992-92-7;5c, 123992-93-8; 5d, 123992-94-9;5e, 123992-95-0; 5f (isomer l), 124095-65-4; 5f (isomer 2), 124095-66-5; 5g, 123992-96-1;SnC1,.2H20, 10025-69-1; HSnCl,, 20265-43-4. Supplementary Material Available: Listings of spectroscopic and analytical data for all compounds listed in Table I (6 pages). Ordering information is given on any current masthead page.
Table I. Catalytic Double Silylation of Ethylene with XMe,SiSiMe,X in the Presence of Pt(PPhd,"
X F CHBO
c1
CH,
electronea of X
vield/90b
3.93 3.70 3.19 2.30
95.0 52.6 48.7 18.0
electro-
X neg of X yield/ 90* P-CF~C~H, 16.4 2.70
C6H5
P-CH~C~H~
4.3 3.8
Conditions: XMe2SiSiMe2X, 1 mmol; Pt(PPh3),, 0.04 mmol; benzene, 3 mL; ethylene, 5 atm a t room temperature; 150 O C ; 22 h. bGC yield.
et al. have disclosed insertion of isocyanides into Si-Si linkages, a new useful variation of double ~ilylation.~ In spite of the renewed interest along this line, however, successful double silylation of simple olefinic compounds has never been reported. Now, we have found that double silylation of ethylene with disilanes proceeds in the presence of platinum phosphine complexes to give 1,2-bis(si1yl)ethanes. In a typical experiment, a benzene (3 mL) solution of 1,2-difluoro-1,1,2,2-tetramethyldisilane (1 mmol) and Pt(PPh,), (0.04 mmol) was treated with ethylene (5 atm a t room temperature) in an autoclave (27 mL) at 150 OC for 22 h. GC analysis showed that 1,2-bis(fluorodimethyIsily1)ethane was formed in 95.0% yield. The product was phenylated (8O.O0/, GC yield) with phenyllithium, and 1,2-bis(dimethylphenylsilyl)ethane*was isolated in 68.5% ' yield.
[Ptl
Platinum-Complex-Catalyzed Double Sllylatlon of Ethylene and Norbornene with Dlsllanes Teruyukl Hayashi, Toshl-akl Kobayashi, Apareclda M. Kawamoto, Hlroshi Yamashita, and Masato Tanaka" National Chemical Laboratory for Industry Tsukuba, Ibaraki 305, Japan Received September 26, 1989
Summay: Double silylation of ethylene with disilanes was found to proceed in the presence of platinum phosphine complexes to give 1,2-bis(siIyl)ethanes. The reactivity was enhanced by electronegative and sterically less demanding substituents on the silicon atom. The reaction of norbornene suggested cis addition of disilanes to the C=C bond.
Exploitation of silicon-containing polymers has been a subject of growing interest owing to their physical properties and chemical reactivities.l In this respect, double silylation of unsaturated carbon compounds with disilanes appears to be a good prospect since it provides a convenient way to synthesize a,w-bis(sily1) compounds that are possible monomers for silicon-containing polymers. Thus, acetylenes and 1,3- and 1,2-dienes successfully undergo double silylation with disilanes to give 1,2-bis(silyl)ethenes, 1,4-bis(silyl)-2-butenes,and 2,3-bis(silyl)-l-propenes,respectively.2 In addition, very recent publications by Ito (1)(a) West, R.;Maxka, J. In Inorganic and Organometallic Polymers; Zeldin, M., Wynne, K. J., Allcock, H. R., Eds.; ACS Symposium Series 360;American Chemical Society: Washington, DC, 1988;Chapter 2 and references therein. (b) Seyferth, D. In Inorganic and Organometallic Polymers; Zeldin, M., Wynne, K. J., Allcock, H. R., Eds.;ACS Symposium Series 360;American Chemical Society: Washington, DC, 1988;Chapter 3 and references therein.
XMe2SiSiMe2X + CH2=CH2 XMe2SiCHzCH2SiMezX(1) Other sym-tetramethyldisilanes were also subjected to the reaction. The results summarized in Table I reveal that disilanes with more electronegative groups attached to the silicon atom more readily underwent the doublesilylation reaction, as was observed with palladium catalysts in the reactions of acetylenes or dienes.2b-eJpkSteric factors also appear to be important, since 1,1,2,2-tetramethyl-1,2-diphenyldisilane,which should have been more reactive than hexamethyldisilane in view of the higher electronegativity of the phenyl group, in fact exhibited very low reactivity. The enhanced reactivity of 1,2-bis(p-(trifluoromethy1)phenyl)tetramethyldisilaneas compared with that of the parent phenyl analogue is again associated with the trifluoromethyl group being strongly electron withdrawing. The performance of the platinum complexes in the double silylation of ethylene with 1,1,2,2-tetramethyl-l,2diphenyldisilane was improved when a more electron donating and sterically less demanding ligand was used; i.e., (2) (a) Sakurai, H.; Kamiyama, Y.; Nakadaira, Y. J. Am. Chem. SOC. 1975,97,931.(b) Tamao, K.; Hayashi, T.; Kumada, M. J. Organomet. Chem. 1976,114,C19. (c) Watanabe, H.; Kobayashi, M.; Higuchi, K.; Nagai, Y. J. Organomet. Chem. 1980, 186,51. (d) Mataumoto, H.; Matsubara, I.; Kato, T.; Shono, K.; Watanabe, H.; Nagai, Y. J. Organomet. Chem. 1980,199,43.(e) Watanabe, H.; Kobayashi, M.; Saito, M.; Nagai, Y. J. Organomet. Chem. 1981,216,149.(0 Carbon, C.W.; West, R. Organometallics 1983,2, 1801. (9) Sakurai, H.; Kamiyama, Y.; Nakadaira, Y. Chem. Lett. 1975,887. (h) Sakurai, H.; Eriyama, y.; Kamiyama, Y.; Nakadaira, Y. J. Organomet. Chem. 1984,264,229.(i) Tamao, K.; Okazaki, S.; Kumada, M. J. Organomet. Chem. 1978, 146,87. G) Matsumoto, H.; Shono, K.; Wada, A.; Matsubara, I.; Watanabe, H.; Nagai, Y. J. Organomet. Chem. 1980,199,185. (k) Watanabe, H.; Saito, M.; Sutou, N.; Kishimoto, K.; hose, J.; Nagai, Y. J. Organomet. Chem. 1982, 225, 343. (1) Seyferth, D.; Goldman, E. W.; EscudiB, J. J. Organomet. Chem. 1984,271,337. (3) Ito, Y.; Nishimura, S.; Ishikawa, M. Tetrahedron Lett. 1987,28, 1293. Ito, Y.;Matsuura, T.; Murakami, M. J. Am. Chem. SOC.1988,110, 3692. (4)Kobayashi, T.;Hayashi, T.; Yamashita, H.; Tanaka, M. Chem. Lett. 1989,467.
0276-7333190f 2309-0280$02.50f 0 0 1990 American Chemical Society
281
Organometallics 1990,9,281-284 Scheme I 3iSiz
,Si
[Ptl,
[Ptl
I
Sin
P=
\
/
the yield of 1,2-bis(dimethylphenylsilyl)ethaneincreased in the order Pt(PPh,), (yield 4.3%) C Pt(PEt3)4(12.2%) < Pt(PPhMe2)4(30.4%) C Pt(PMe3)4(33.0% ). Palladium complexes such as Pd(PPh3)4and PdC12(PhCN)2,which have been known to be active catalysts for double silylation of acetylenes and dienes, were inactive for the present reaction. Likewise, other complexes such as PtCl2(PPh3I2, PtCl,(PhCN),, RhCl(PPh,),, H2Ru(CO)(PPh3),,and Ru(CO),(PPh3)2were totally inactive. As for the reaction mechanism, the following observations are worth noting. The Si-Si linkage in FMe2SiSiMe2Fand ClMezSiSiMe2Clhas been found to be readily cleaved when treated with Pt(PEt3), at room temperature to give cis-bis(silyl)bis(phosphine)platinum complexes. However, PhMe2SiSiMe2Phseemed ~ n r e a c t i v e . ~ Thus, the reactivities of disilanes toward Pt(PEt3), were in good agreement with those observed in the foregoing catalytic reactions. In addition to these, our previous paper4 has communicated that cis-bis(dimethylpheny1silyl)bis(methyldipheny1phosphine)platinumreadily reacts with ethylene a t atmospheric pressure and room temperature to give the corresponding 1,2-bis(silyl)ethane. On the basis of all these facts combined together, the double silylation is envisaged to proceed via oxidative addition of the disilane, insertion of ethylene into one of the resulting Si-Pt bonds, and reductive elimination of 1,2bis(sily1)ethane from the silyl(0-silylethy1)platinum intermediate as in Scheme I. To see the stereochemistry of the addition, norbornene was allowed to react with 1,2-difluoro-1,1,2,2-tetramethyldisilane under the same conditions as above. 2,3Bis(fluorodimethylsily1)norbornane was formed in 26.0% yield, which was methylated with methyllithium to give 2-ex0,3-exo-bis(trimethylsilyl)norbornane.~ The result is rationalized by the cis addition of the disilane via coordination of the platinum center on the less hindered olefinic face. In summary, this paper reports the first successful examples of double silylation of simple olefins, which offers a convenient way for the synthesis of silicon-containing ( 5 ) Details will be published elsewhere.
(6) High-resolution MS: found M+, 240.1736; calcd for CI3H&3i2, 240.1729. MS (EI, m / z (relative intensity)): 240 (M+, 2), 167 ( l l ) , 151 (3), 131 (6), 124 (5), 109 (3), 101 (2), 73 (100). 'H NMR (200 MHz, C&&: 6 0.14 ( 8 , 18 H, SiCH,), 0.89 (d, J = 1.7 Hz, 2 H, SiCH), 1.05-1.38 (m, 4 H, methylene CH2,ethylene CH (endo)),1.61-1.73 (m, 2 H, ethylene CH (exo)), 2.25-2.33 (m, 2 H, bridgehead CH) ppm. 13C NMR (CsDa): 6 0.5 (SiCHJ, 34.3,36.0,38.4,40.1 (norbornane) ppm. 'H COSY measurement revealed that the splitting of the silyl-substituted methine proton signal into a doublet was due to the coupling with the anti proton at the bridging methylene and that its coupling with the bridgehead proton was not observed. These results combined with precedents' verify the 2-exo,3-exo geometry of the bis(sily1) groups. (7) (a) Laszlo, P.; Schleyer, P. v. R. J.Am. Chem. SOC.1964,86, 1171 and references cited therein. (b) Kuivila, H. G.; Warner, C. R. J. Org. Chem. 1964, 29, 2845.
polymers. For instance, 1,2-bis(chlorodimethyIsilyl)ethane could be polymerized by Wurtz type condensation with sodium to give copoly(tetramethyldisilene-ethy1ene) with M, = 192 OO0.8 An investigation on reactivities of other types of olefins toward disilanes is now in progress. Registry No. FMezSiSiMe2F,661-68-7;(MeO)MezSiSiMe24342-61-4;Me3SiSiMe3, (OMe), 10124-62-6;C1MezSiSiMe2Cl, 1450-14-2;(p-CF3C6H4)MezSiSiMez(p-CF3c6H4), 36112-13-7; PhMezSiSiMezPh, 1145-98-8;(p-CH3C6H,)Me2SiSiMez(pC H S C ~ H ~5971-96-0; ), CHz=CHz,74-85-1;Pt(PPh3)4,14221-02-4; FMe2SiCHzCH2SiMezF, 2251-44-7;(MeO)MezSiCHzCH2SiMez(OMe), 76490-69-2;C1Me2SiCHzCHzSiMe2C1, 13528-93-3; Me3SiCH zCHzSiMe3, 623 1-76-1; ( p -C F 3 C 6 H 4 ) MezSiCHzCHzSiMez(p-CF3C6H4),123857-50-1; P hMezSiC HzCH2SiMezP h, 15527-45-4; ( p -C H 3 C 6 H 4-) Me2SiCHzCH2SiMez(p-CH3C6H4), 123857-51-2;Pt(PEt3)4, 33937-26-7;Pt(PPhMez)4,33361-89-6;Pt(PMe3)4,33937-27-8; norbornene, 498-66-8;2-exo-3-exo-bis(fluorodimethylsilyl)norbornane,123857-52-3; 2-exo-3-exo-bis(trimethylsilyl)norbornane, 123857-53-4. (8) Tverdokhlebova, I. I.; Sutkevich, 0. I.; Ronova, I. A.; Polyakov, Yu. P.; Gusel'nikov, L. Ye.; Pavlova, S. A. Vysokomol. Soedin.,Ser. A 1988, 30, 1070.
Formation of Cyclic Carbosilanes in the Pyrolysis of Octamethyltrisilane Brigitte Nebout BortolIn,+ Ialn M. T. Davldson,'mt: Denls Lancaster,$Terry Slmpson,f and Deborah A. Wildt: Deparment of Chemistry, The University Leicester LE 1 7RH, Great Britain, and Dow Corning Sussex Research School of Molecular Sciences, University of Sussex Brighton BN 1 9QJ, Great Britain Received May 19, 1989
Summary: Prominent products in the pyrolysis of the title compound are cyclic carbosilanes; evidence is presented that one of these is formed in a novel and potentially useful elimination reaction.
The mechanism of breakdown of polysilanes is of interest because of their importance as photoresists' and as potential precursors to new polycarbosilane polymers. Accordingly, we are undertaking a study of the gas-phase pyrolysis of volatile permethylated polysilanes as model compounds and now report our initial results with octamethyltrisilane, Me8%, (1). Me8&, was pyrolyzed by our stirred-flow (SFR) technique2 between 558 and 655 "C with partial pressures of 0.25-0.9 mmHg in helium or nitrogen carrier gas. The SFR apparatus attached to a GC/mass spectrometer (HP5995C)2was used for identification of products. The major product was Me,SiH, with smaller quantities of other monosilanes (Me2SiH2and Me4Si), but the main 'Dow Corning, Sussex. *University of Leicester.
0276-7333/90/2309-0281$02.50/00 1990 American Chemical Society
